New Caribbean disturbance 93L a major concern; flooding in Asia kills over 200

A concentrated region of intense thunderstorms associated with a tropical wave has developed in the central Caribbean, a few hundred miles south of Puerto Rico. This disturbance was designated Invest 93L by NHC this morning, and has the best chance to become Tropical Storm Alex of any system we've seen so far this year. The disturbance is located near Buoy 42059, and this buoy has been reporting winds of 5 - 15 knots this morning. So far, pressures are not falling. Water vapor satellite loops show that 93L is embedded in a large region of moist air. Some dry continental air from North America is over the western Caribbean, but this dry air is too far away to interfere with development today and Tuesday. Wind shear is a low 5 - 10 knots. The high wind shear associated with the strong winds of the subtropical jet stream are over the northern Caribbean, too far north to interfere with development. Sea Surface Temperatures are plenty warm, a record 29 - 30°C. The Madden-Julian oscillation currently favors upward motion over the Caribbean, which will act to increase the chances of tropical storm formation this week. The Madden-Julian oscillation is a pattern of enhanced rainfall that travels along the Equator from west to east. The pattern has a wet phase with large-scale rising air and enhanced thunderstorm activity, followed by a dry phase with large-scale sinking air and suppressed thunderstorm activity. Each cycle lasts approximately 30 - 60 days. When the Madden-Julian oscillation is in its wet phase over a hurricane-prone region, the chances for tropical storm activity are greatly increased. The only negative for 93L would seem to be the lack of spin; the University of Wisconsin 850 mb relative vorticity analysis is showing only meager amounts of spin at 850 mb (roughly 5,000 feet in altitude.)

Forecast for 93LNHC is giving 93L a 20% chance of developing into a tropical depression by Wednesday morning, which is a reasonable forecast. With wind shear expected to drop to low values less than 10 knots over the central and western Caribbean this week (Figure 2), I don't see any major impediments to the storm becoming a tropical depression by Friday. The ECMWF model is the most aggressive in developing this system, taking it into the Gulf of Mexico as a hurricane next week. The NOGAPS model keeps the storm weak and farther south, predicting that 93L will bring heavy rains to northern Honduras as a tropical disturbance or tropical depression on Friday and Saturday. The GFS model does not develop 93L. Expect 93L to bring flooding rains of 3 - 6 inches to Jamaica, eastern Cuba, and extreme southwestern Haiti on Wednesday. These rains will spread to the Cayman Islands and central Cuba by Thursday.

Figure 2. Predicted wind shear for Friday, June 25, as forecast by this morning's 2am EDT run of the GFS model. Shear is given in meters per second; multiply by about two to convert to knots. Low wind shear values less than 6 m/s (12 knots) are predicted for much of the Western Caribbean this week.

Elsewhere in the tropicsThe tropical wave (92L) that brought heavy rains of 2 - 5 inches to Puerto Rico on Saturday has weakened and is no longer a threat to bring flooding rains to the Caribbean.

Floods in China and Burma kill over 200The deadliest and most destructive weather-related disaster on the planet so far this year is occurring in southern China and northern Burma, where a week of heavy rains has caused flooding that has claimed over 200 lives. The death toll stands at 175 in China and 63 in Burma, with more than 100 people still missing in China. Damage so far in China has been estimated at $4.3 billion.

Montana tornado rips roof off entertainment complexA EF-2 tornado with winds of at least 100 mph ripped the roof of an entertainment complex in Billings, Montana on Sunday, causing up to $15 million in damage. No injuries were reported. It was the strongest tornado to hit the Billings area since 1958.

Figure 4. Video of the Billings tornado shows an impressive debris cloud (and a few expletives not deleted!) The clear slot on the right of the tornado is likely associated with the parent thunderstorm's rear flank downdraft.

Wind and ocean current forecast for the BP oil disasterSoutheast to east winds less than 10 knots will blow in the northern Gulf of Mexico today through Friday, according to the latest marine forecast from NOAA. The resulting weak ocean currents should cause little motion of the oil slick, according to the latest trajectory forecasts from NOAA and the State of Louisiana. The long range outlook is uncertain, as the tropical wave over the central Caribbean could enter the Gulf of Mexico early next week and develop into a tropical storm.

Quoting MiamiHurricanes09:Upper level steering, I think, is felt when a system attains a pressure of 950 millibars or below, not sure though.

Not at all, even a strong tropical storm weak hurricane will feel the trough the GFS and Euro are advertising. Now if we had a deeper ridge and shallow trough, then a strong hurricane could even take advantage of that.

I completely disagree. Any hurricane can feel a weakness in created by a trough. Granted this trough is most likely not that strong 93L has plenty of time to strengthen in order to feel a weakness in the atmosphere

Last I checked for the trough to create the weakness in the upper level ridge it has to be in the upper levels.

I guess I am looking at this wrong. I am looking at the system as if it were a "regular" sized "wave" as it were and missing the features i should be seeing.

Could it be that the general features are so spread apart that it is difficult to put together, and if so, when might one expect to see the system tighten up some, and presumably strengthen at the same time. if indeed that happens.

everything points to this becoming a strong hurricane while still in Caribbean. The SHIPS brings it to 114 MPH hurricane in 120 hours when it will still be in Caribbean. Chances are 93L will become the first hurricane of the 2010 hurricane season and eventually the first major hurricane.

Lookig at models my opinion is that it will be strong enough to feel weakness of trough and unfortunately be more of a threat to the central and eastern GOM rather than Texas

I think you are exaggerating a little there, although conditions are forecasted and are currently are favorable I just can't say that an invest might become a major hurricane, too much uncertainty right now.

Floodman,You must have me confused with someone else. I AM NOT taking anything SERIOUS at this point. I realize that these things take time and anything can happen. So... Just for the record I do Not believe ANYONE is taking ANYTHING serious at this time..We are just searching for information and staying informed.

Quoting MiamiHurricanes09:I believe it has to have a pressure of around 950 millibars to feel upper level steering.

I completely disagree. Any hurricane can feel a weakness in created by a trough. Granted this trough is most likely not that strong 93L has plenty of time to strengthen in order to feel a weakness in the atmosphere

I'll say one thing, 93L is taking the shape of true tropical cyclone regardless of the other lacking criteria, that in itself is strong sign of a favorable environment for steady organization and development.

Quoting MiamiHurricanes09:There isn't any banding there. Thunderstorm activity is waning thus thunderstorms are collapsing which shows that outflow in the upper levels, that outflow might be what you are mistaking with banding.

No, we discussed it earlier with Levi. It's actual banding. There are bands to the east feeding into the system and bands to the northwest.

Must be some powerful.@#$%....Either way, it looks more likely than not that some area bordering the Gulf is going to get whacked with a hurricane. Whether its 93L or not. I could be labeled a down-caster, after all more than one landfall is being predicted.

Quoting MiamiHurricanes09:Yes but unless it is a "STRONG" hurricane it won't feel it. I have yet to see proof (that is believable) of a strong hurricane while it's still in the Caribbean.

low shear, insane TCHP, model support, high SST's

everything points to this becoming a strong hurricane while still in Caribbean. The SHIPS brings it to 114 MPH hurricane in 120 hours when it will still be in Caribbean. Chances are 93L will become the first hurricane of the 2010 hurricane season and eventually the first major hurricane.

Lookig at models my opinion is that it will be strong enough to feel weakness of trough and unfortunately be more of a threat to the central and eastern GOM rather than Texas